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Dynamo Hmm...

Posted by ChazzyB <iframe src='https://members5.boardhost.com/classicbikemart/info/user=ChazzyB' width='330' height='300' border=0 style='border:none;'> on December 31, 2024, 5:07 pm

Firstl, a trigger warning - this post may contain old bike mumblings.

Having been galvanised (did you see what I did there?) into action to change my AJS 18S' E3L dynamo armature (should be an short E3N) , I set to work. However, things as ever are never quite straightforward with old bikes.

The dynamo itself has a Lucas part number 20036 on the shell, so for BSA, and I have found 200712 stamped on the armature - again suitable for a BSA A7/A10.

Now then, a Lucas 200712 armature should have a parallel drive end shaft with no extrnal threaded section, just a threaded hole at the end for a retaining bolt. Mine is just like that, except the end is tapered...

I'm guessing some bodger in the dim and distant past has "machined" a taper onto the drive end of the armature of a BSA dynamo. I'm also guessing that "machining" could be why I see a wobble as it turns, which lead me to believe the armature was bent. The "taper" is covered in gouge marks, which can't help. I might try lapping the sprocket the shaft with grinding paste.

Oh, and the bearings on the shaft are well knackered too. In fact, comprehensively so.

HNY, y'all.

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Re: Dynamo Hmm...

Posted by ChazzyB <iframe src='https://members5.boardhost.com/classicbikemart/info/user=ChazzyB' width='330' height='300' border=0 style='border:none;'> on December 31, 2024, 5:10 pm, in reply to "Dynamo Hmm..."

And a Goldstar to anyone who works outs the thread title reference.

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Re: Dynamo Hmm...

Posted by Brickboy <iframe src='https://members5.boardhost.com/classicbikemart/info/user=Brickboy' width='330' height='300' border=0 style='border:none;'> on December 31, 2024, 5:26 pm, in reply to "Re: Dynamo Hmm..."

Oh dear... that sounds like a rather substantial fix to me.

Dynamoan? Hmmm? No Goldstar for me, I guess.

This is why I often sell classics after a short duration. I start to imagine what might go wrong and how infuriating it might be... Then they go before they can demonstrate just how perfect they were if only I'd realised!

My 18S is awaiting the return of its speedo with a fully functional trip meter - ah, the joyous thoughts of that!

Good luck with yours, Chazzy - I know mine was rebuilt by Tony Cooper so it might be the best bit of the bike!!

HNY to you all, as well!!

Re: Dynamo Hmm...

<<Dynamoan? Hmmm? No Goldstar for me, I guess.>>

Quite right, no.

Next!

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Re: Dynamo Hmm...

Is Tony Cooper still working? Top chap.

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Re: Dynamo Hmm...

Posted by Hants Ian <iframe src='https://members5.boardhost.com/classicbikemart/info/user=Hants+Ian' width='330' height='300' border=0 style='border:none;'> on December 31, 2024, 6:28 pm, in reply to "Re: Dynamo Hmm..."

Tapered armatures are used on BSA twins with a treaded section for the nut to hold the drive sprocket on. Similar one used on later Velocettes, only they use a pulley.

The light at the end of the tunnel maybe an oncoming train

Re: Dynamo Hmm...

Think so 01215 592405

Re: Dynamo Hmm...

Posted by Tonupdave <iframe src='https://members5.boardhost.com/classicbikemart/info/user=Tonupdave' width='330' height='300' border=0 style='border:none;'> on December 31, 2024, 6:50 pm, in reply to "Re: Dynamo Hmm..."

Two dynamo I have have tapered shafts the Ariel one is the short dynamo have a long one that also fits the Ariel my trouble is the old regulator never got around to fittinga new one..

Tonupdave..T.U.D.

Re: Dynamo Hmm...

Posted by spriddler <iframe src='https://members5.boardhost.com/classicbikemart/info/user=spriddler' width='330' height='300' border=0 style='border:none;'> on January 1, 2025, 11:14 am, in reply to "Re: Dynamo Hmm..."

Parallel shaft is for the pinion on twins. A replacement is an E3L 6v armature with a tapered shaft for the keyed sprocket.